Spider silk is a natural protein fiber produced by the spiders. Despite being a biopolymer, spider silk's tensile strength is comparable to that of high-grade alloy steel, but it has only about a sixth of the density of steel. Spider silk has been used by humans for many, many years. The ancient Greeks used it to stop wounds from bleeding. Optical targeting devices and fishnets are more recent applications of spider silks. The current study of spider silk opens the potential use of spider silks in strong and biodegradable materials such as wear-resistant lightweight clothing, rust-free panels on cars, and some biomedical devices.
Because spiders are hard to farm like silkworms in high densities because of their carnivorous nature, it is difficult to produce large amount of spider silks from farm-raised spiders. Genetic engineering is an alternative approach to produce large quantities of spider silk for commercial applications. The relevant genes of spiders have been cloned and inserted into several different organisms, such as E. coli, alfalfa, goat and silkworm, to make spider silks by different groups. Producing large-scale truly spider-like silk, however, remains a big challenge due to the small protein size, low yield and low water solubility of bio-synthetic spider silk.